mm/hugetlb.c: avoid bogus counter of surplus huge page

If we have to hand back the newly allocated huge page to page allocator,
for any reason, the changed counter should be recovered.

This affects only s390 at present.
Signed-off-by: Hillf Danton <dhillf@gmail.com>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/hugetlb.c

@@ -800,7 +800,7 @@ static struct page *alloc_buddy_huge_page(struct hstate *h, int nid)
 
 	if (page && arch_prepare_hugepage(page)) {
 		__free_pages(page, huge_page_order(h));
-		return NULL;
+		page = NULL;
 	}
 
 	spin_lock(&hugetlb_lock);